Are the following sentences natural to a native ear?
1. Would you have rather preferred that I finished my task before helping him?
2. Interpol warned of possible retaliatory attacks for / against the killing of Osama.
3. I was taught not to speak with a mouthful.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.